The present invention relates to a method of recording a hologram.
Holograms are recently finding more use as optical elements such as hologram lenses, hologram scanners and the like in various optical devices. As optical elements, holograms are required to be optically equivalent to each other. As regards hologram disks used in hologram scanners, they must be optically equivalent to each other for compatibility, and holograms on one hologram disk must also be optically equivalent to each other.
Holograms have heretofore been recorded or photographed under fixed exposure conditions.
Holograms are recorded on a recording medium comprising a recording material coated as a thin layer on a substrate of glass or plastics. In order to be optically equivalent, holograms are made on the same recording material. However, the properties of the recording material used vary slightly as the environment changes from time to time. The manner in which the recording material is processed by exposure to light varies dependent on the condition in which the recording material has been coated, the surface condition of the substrate, the thickness of the recording material layer, and other factors. If the exposure conditions should be fixed, the diffraction efficiencies of the recorded holograms would tend to be different due to recording material irregularities such as changes in the material properties, irregular thicknesses of the coated layer, and the like.